Hey Tep,just tried your circuit (again). Like before, the opto seems to function(via LED) but my arduino read nothing. I have already tried different resistor combos with the (working)cny17-4. As far as I can tell, it seems pretty forgiving, midi data gets through every time. There has to be some hardware problem going on here. It doesnt read midi even when the opto is bypassed and the midi connected directly to the arduino. THis should work. There is no need for any kind of filter or anything, is there?

Oh, another thing....I may have already mentioned this , but I did get a 4n28 to work,once.I dont know what I did, but after like, the umpteenth build it just worked, briefly...until I disconnected the rx lead. When I put it back in place it would no longer communicate. At first I though that it was definately a continuity issue but everything checked out, and since it works fine now with a cny17-4, i know it cant be bad or loose connection.

As said before a few times:[glow]A lot of MIDI devices don't use NOTE OFF messages but NOTE ON with VELOCITY 0.[/glow]That's the main issue related.Check that out, add a verification of the velocity before the action to switch to action 0 if the velocity is 0 !

(and/or connect the two interfaces together and read the raw MIDI to be sure about it.)

Hi. First of all please excuse my English. For a long time I've being searching for a way to convert MIDI code to plain text. I've found some software but what I really need is to isolate ONLY a list of all Note-On data in the same order they are played. I don't need Velocity, Note-Off Channel Number, Duration, etc. Also need the posibility to transport (change to the other 11 semitones pitch) the whole data. I'm talking about a monodic track (only one voice). For example, to open a MIDI file from Mozart's Piano Sonata first two bars, and to get back this: [C5,E5,G5,B4,C5,D5,C5] But also beguining from [C#5...etc] and [D... etc] and from all the other 11 transposed chromatic steps. This is for Musical Research to found melodic-thematic similarities between within other works from the same or different composers. Could someone give any help to find something near this? I know Peter Van Oostrüm and Günter Nagler's and Go-Minimal software but I can't isolate Note-On data from the rest.Thank You.

Also the 4N28 optocoupler did not work in any configuration for me. I could verify the chip itself was working fine using the test circuit on this page [1] and I verified the Arduino Rx worked fine and MIDI signal was fine. I did finally get things working with the CNY17-4 optocoupler though.

Here is the configuration that ended up working for me:Arduino Duemilanove connected to Macbook USBM-Audio Keystation 61esSchematic in the original post of this thread, substituting CNY17-4 for 4N28

Really strange about the 4N28. No idea why it would not work in this configuration other than some sort of variation between manufacturers [2].

I'm sorry I can't point you to some literature, but you could have a look at the FTDI chip datasheet and and MIDI specifications.I've used Motorolas 4N28 an 4N35, the white ones and it works.Did you try the schematic I did post here?http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1187962258/60#71The one in the first post seems to work only for the poster, many people have the same problem: No 100k & GND connection on 4N28 pin 1!